The present invention relates to a system for in situ refining elements to very low impurities; more particularly, refining high purity elements to further reduce impurities. Still more particularly, the invention relates to a method and apparatus for the preparation of high purity elements of Groups IIA and VIB of the Periodic Table of Elements.
It is desirable for many applications to provide high purity material exceeding 99.9999% purity, and to reduce impurity levels of certain contaminants to one part per billion atomic (ppb) or less. For example, the performance of infrared devices is adversely affected by the presence of impurities, even some impurities in the parts or subparts per billion range.
Many techniques have been proposed to produce high purity material, including purification techniques using distillation and/or zone refining. However, these techniques have not adequately eliminated certain critical impurities to the extent desired. The technique itself may be insufficient or contamination may occur in the purification process or in transfer of material between purification treatments.
The present invention combines distillation and zone refining in such a way as to reduce impurity levels to extremely low values.